If there is a computer or sophisticated electronics plugged into a surge protector and the outlet is more than a twenty years old, it may be a good idea to replace it. A new outlet will have better electrical and ground contacts.
In many older homes three pronged grounded type outlets have been added by a previous homeowner for the convenience of being able to plug in appliances with a three pronged plug. It is quite common that these newly added outlets do not have a ground wire connected to them!
A surge protector plugged into one of these outlets will not operate as the manufacturer intended. When a large surge or spike hits, the surge protector uses the ground wire to take the "hit" away safely to ground. If the surge or spike is not sent to ground by the surge protector it will continue on and bypass the surge protector. A hit by a surge can do tremendous damage to your electronics.
NOTE: The warranty that the surge protector manufacturers offer, is only valid if the surge protector is used in a properly grounded outlet.